The NSABP as a research group has shown by the use of the prospective randomized clinical trial that: 1) Local therapy as indicated by Protocol B-04, a comparison of Radical Mastectomy versus Total Mastectomy versus Total Mastectomy with postoperative irradiation has no significant influence on disease-free interval or survival. 2) Adjuvant therapy as indicated by Protocol B-05, a comparison of L-Pam versus placebo in histologically proven Stage II patients has significantly prolonged the disease-free interval and survival in a subset of women, 19 years or younger. As a participating institution in NSABP, we have and will continue to make major contributions to: 1) Protocol B-06, which is designed to determine whether local therapy in the form of Total Mastectomy or Segmental Mastectomy plus breast irradiation is comparable to Segmental Mastectomy. All patients will undergo axillary node dissection and those with metastatic nodes will receive two drugs, L-Pam and 5FU as adjuvant therapy. 2) Protocols B-07 (L-Pam vs. L-Pam and 5FU), B-08, (L-Pam and 5FU vs. L-Pam and 5FU and Methotrexate) and B-09 (L-Pam and 5FU vs. L-Pam and 5FU and Tamoxifen). These protocols are designed to determine whether combination adjuvant therapy can further improve the disease-free period and survival involving chemotherapy and anti-estrogen hormonal therapy. This institution seeks further funding to continue: 1) accrual of patients in ongoing clinical trials, 2) close follow-up of patients already entered into above protocols, 3) to obtain information and specimens relevant to these trials, 4) collaborative studies with other researchers, and 5) input into new protocols. The basic purpose of this proposal is to attempt to improve the disease-free interval and survival of the women with breast cancer by the multi-disciplinary approach and secondarily to educate medical students and colleagues in practice that the prospective randomized clinical trial is the best way to obtain sound and meaningful data.